1. Field of the Invention
This invention relates to non-ionic surface-active agents containing carbonate and carboxylic ester groups.
2. Description of the Prior Art
A wide variety of non-ionic surface-active agents are known in the art. Usually, these are stable in acid, basic and neutral media. In addition, many non-ionic surface-active agents are not easily biodegraded making such surface-active agents a source of water pollution. In some applications, it is necessary or at least highly desirable to modify or change the surface activity of a surface-active agent at some critical point in an operation utilizing such agents. For example, in the recovery of oil and waxes from raw wool by emulsification there is obtained an emulsion in water which is not easily broken so as to allow recovery of the oils and waxes for the purposes of disposal. In addition, commercial laundry effluents containing non-ionic surface-active agents are a source of water pollution. In the recovery of petroleum, emulsions are formed which are not easily broken without the use of certain complex and expensive demulsifying agents.
The present surface-active compounds are suited for use under the conditions described above and yet can be changed in surface activity properties by treatment with a dilute basic compound and/or heating in order to degrade the surface-active compounds by hydrolytic cleavage of the molecule. The present compounds can be made so as to exhibit low or high foaming, good detergency, and low or high cloud points as desired.
In U.S. Pat. No. 4,072,704, there are disclosed multi-block coupled polyoxyalkylene copolymer surfactants prepared by reacting bifunctional compounds to form polycarbonate esters. These materials are formed of polyoxyalkylene units coupled by reaction with an alkyl carbonate such as diethyl carbonate. There is no indication that monofunctional alcohols are useful in the preparation of such surfactants. Biodegradable, alkali-stable, non-ionic surfactants are disclosed in U.S. Pat. No. 4,207,421 as containing the residues of a linear aliphatic alcohol, ethylene oxide, and a propylene oxide or butylene oxide residue cap.
High molecular weight polycarbonates are disclosed in U.S. Pat. No. 3,248,414; U.S. Pat. No. 3,248,415; and U.S. Pat. No. 3,248,416. These are prepared, for instance, by reacting ethylene carbonate and ethylene oxide in the presence of a basic catalyst. The hydroxyl-terminated compositions range in molecular weight from 700 to 5000 and react with isocyanates to form urethanes.